The present invention relates to low-foaming nonionic surfactants and more particularly to ether-capped poly(oxyalkylated) alcohol surfactants which have superior spotting and filing benefits in dishwashing and hard surface cleaning applications, as well as suds suppression in detergent applications.
1. Background of the Invention
Dishwashing and hard surface cleaning, in particular automatic dishwashing in domestic appliances, is an art very different from fabric laundering. Domestic fabric laundering is normally done in purpose-built machines having a tumbling action. These are very different from spray-action domestic automatic dishwashing appliances. The spray action in the latter tends to cause foam. Foam can easily overflow the low sills of domestic dishwashers and slow down the spray action, which in turn reduces the cleaning action. Thus in the distinct field of domestic machine dishwashing, the use of common foam-producing laundry detergent surfactants is normally restricted. These aspects are but a brief illustration of the unique formulation constraints in the domestic dishwashing and hard surface cleaning fields.
One solution to this foaming problem has been to include a suds suppressor, typically a silicone suds suppressor. However, this solution while it works to a certain extent in fabric laundering compositions, fails in domestic dishwashers. The high shear forces involved in domestic dishwashers breaks down the silicone suds suppressors, so any suds suppressors present at the start of the wash is gone before the end. The silicone suds suppressors are not robust enough to survive in the environment of a domestic dishwasher. Even in laundry applications, while less shear than that in a domestic dishwasher, there is still a drop off in suds suppression towards the end of the washing cycle, because of the break down of the silicone suds suppressor. One alternative would be increase the amount of silicone suds suppressor present, however the cost of silicone suds suppressors and the fact that they have a tendency to redeposit on hydrophobic surfaces, such as plastic, makes this an undesirable solution. There remains today the need for a viable and cost effective alternative to silicone suds suppressor suitable for use in automatic dishwashers as well as laundry washing machines.
On account of the foregoing technical constraints as well as consumer needs and demands, these compositions are undergoing continual change and improvement. Moreover environmental factors such as the restriction of phosphate, the desirability of providing ever-better cleaning results with less product, providing less thermal energy, and less water to assist the washing process, have all driven the need for improved compositions.
However, many compositions heretofore proposed for cleaning dishware and hard surfaces have had aesthetic and technical disadvantages, not the least of which is undesirable spots and films on the cleaned surfaces. These undesirable spots and films may be caused by redeposition of soils and cleaning agents such as surfactants which have a low solubility in water. In addition, there continues to be a need for better cleaning, especially for reduction of spots and films and in some cases removal of greasy soils. This need is driven by consumer demand for improving performance from the cleaning compositions spotting and filming benefits and on hard to remove greasy soils.
Accordingly, the need remains for low-foaming surfactants which can deliver improved spotting and filming reduction benefits while providing greasy soil removal as well as providing suds suppression which is robust enough to survive the washing environment in which it is deployed.
2. Background of the Invention
U.S. Pat. No. 4,272,394, issued Jun. 9, 1981, U.S. Pat. No. 5,294,365, issued Mar. 15, 1994 U.S. Pat. No. 4,248,729, issued Feb. 3, 1981; U.S. Pat. No. 4,284,532, issued Aug. 18, 1981; U.S. Pat. No. 4,627,927, issued Dec. 9, 1986; U.S. Pat. No. 4,790,856, issued Dec. 13, 1988; U.S. Pat. No. 4,804,492, issued Feb. 14, 1989; U.S. Pat. No. 4,770,815, issued Sep. 13, 1989; U.S. Pat. No. 5,035,814, issued Jul. 30, 1991; U.S. Pat. No. 5,047,165, issued Sep. 10, 1991; U.S. Pat. No. 5,419,853, issued May 30, 1995; U.S. Pat. No 5,294,365, issued Mar. 15, 1994; GB Application No. 2,144,763, published Mar. 13, 1985; GB Application No. 2,154,599, published Sep. 9, 1985; WO Application No. 9,296,150, published Apr. 16, 1992; WO 94/22800, published Oct. 13, 1994, WO 93/04153, published Mar. 4, 1993, WO 97/22651, published Jun. 26, 1997, EP Application No. 342,177, published Nov. 15, 1989 and xe2x80x9cGlyceryl Bisether Sulfates. 1: Improved Synthesisxe2x80x9d Brian D. Condon; Journal Of the American Chemical Society, Vol. 71, no. 7 (July 1994).
This need is met by the present invention wherein a low-foaming nonionic surfactant is provided. The low-foaming nonionic surfactant, either alone or in combination with other surfactants, provides improved spotting and filming performance as well as improved cleaning performance on greasy soils and suds or foam suppression in certain applications. While not wishing to be bound by theory, it is believed the alcohol surfactants of the present invention deliver superior spotting and filming benefits via improved sheeting action. As for improved cleaning performance on greasy soils, such benefits are shown when the alcohol surfactants of the present invention are employed in conjunction with a high cloud point nonionic surfactant as disclosed in detail herein. Lastly, the alcohol surfactants of the present invention may also act to reduce the suds or foaming associated with food soils or various other cleaning agents and allow the use of soluble surfactants, which are high sudsing, such as amine oxides.
In accordance with a first aspect of the present invention, an ether-capped poly(oxyalkylated) alcohol surfactant is provided. The alcohol has the formula:
R1O[CH2CH(R3)O]x[CH2]kCH(OH)[CH2]jOR2
wherein R1 and R2 are linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from about 1 to about 30 carbon atoms; R3 is H, or a linear aliphatic hydrocarbon radical having from about 1 to about 4 carbon atoms; x is an integer having an average value from 1 to about 40, wherein when x is 2 or greater, R3 may be the same or different and k and j are integers having an average value of from about 1 to about 12, and more preferably 1 to about 5, further wherein when x is 15 or greater and R3 is H and methyl, at least four of R3 are methyl, further wherein when x is 15 or greater and R3 includes H and from 1 to 3 methyl groups, then at least one R3 is ethyl, propyl or butyl, further wherein R2 can optionally be alkoxylated, wherein said alkoxy is selected from ethoxy, propoxy, butyloxy and mixtures thereof.
R1 and R2 are preferably linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from about 6 to about 22 carbon atoms with about 8 to about 18 carbon atoms being most preferred. R2 can optionally be alkoxylated, wherein the alkoxy is selected from ethoxy, propoxy, butyloxy and mixtures thereof H or a linear aliphatic hydrocarbon radical having from about 1 to about 2 carbon atoms is most preferred for R3. Preferably, x is an integer having an average value of from about 1 to about 20, more preferably from about 6 to about 15. Also, preferred in the present invention are alcohol surfactants as described above wherein the cloud point of the surfactant is less than about 20xc2x0 C.
In accordance with a second aspect of the present invention, a method of suds suppression is provided. The method comprises the step of adding an effective amount of a suds suppressing surfactant to an aqueous cleaning solution, the surfactant comprising an ether-capped poly(oxyalkylated) alcohol surfactant. The alcohol has the formula:
R1O[CH2CH(R3)O]x[CH2]kCH(OH)[CH2]jOR2
wherein R1, R2, R3, x, k and j are hereinbefore defined. Preferably, the aqueous cleaning solution is present in a washing appliance, such as an automatic dishwasher. An effective amount of the suds suppressing surfactant is added to the aqueous cleaning solution, preferably from about 0.1% to about 15% more preferably from about 0.1% to about 10%, even more preferably 0.5% to about 5% by weight
As already noted, the invention has advantages, including superior spotting and filming reduction benefits and greasy soil removal, good dishcare, suds suppression and good overall cleaning.
Accordingly, it is an aspect of the present invention to provide a low-foaming nonionic surfactant having superior spotting and filming reduction benefits and excellent greasy soil removal, good dishcare, suds suppression and good overall cleaning. It a further aspect of the present invention to provide an ether-capped poly(oxyalkylated) alcohol surfactant. It is a further aspect of the present invention to provide a surfactant which suppresses or reduces the suds associated with food soils, for example egg soils, or various other cleaning agents, for example other surfactants. These and other aspects, features and advantages will be apparent from the following description and the appended claims.
All parts, percentages and ratios used herein are expressed as percent weight unless otherwise specified. All documents cited are, in relevant part, incorporated herein by reference.